The present disclosure relates to a vibration generating apparatus.
A vibration generating apparatus, converting electric energy into mechanical vibrations using a principle of generating electromagnetic force, has been mounted in mobile phones to thereby be used for silently notifying a user of call reception by transferring vibrations thereto.
Meanwhile, in accordance with the rapid growth in a mobile phone market and the trend toward the addition of several functions to mobile phones, mobile phone components have been required to be compact while being high quality. In accordance with this trend, the necessity of developing vibration generating apparatuses having novel structures capable of overcoming disadvantages of existing vibration generating apparatuses and significantly improving quality has increased.
In addition, recently, in many markets, mobile phones have been replaced by smart phones in which a touch screen scheme is adopted. Therefore, the use of vibration generating apparatuses, provided for the purpose of generating vibrations at the time of a user touch, has increased.
Levels of performance particularly required of vibrations generated at the time of touching a touch screen are as follows. First, since the number of vibrations generated at the time of touching the touch screen is larger than that of vibrations generated at the time of call reception, an effective operational lifespan of a vibration generating apparatus should be lengthened. Second, in order to increase user satisfaction when a user experiences vibrations at the time of touching the touch screen, a response speed of the vibrations should increase in accordance with a user's speed in touching a touch screen.
In addition, a piezo haptic actuator has been used as a device capable of implementing such performance. Such a piezo haptic actuator uses the principle of an inverse piezoelectric effect in which displacement is generated in the case that a voltage is applied to a piezo-element, that is, the principle of allowing a mass body to be moved by the generated displacement to generate vibratory force.
A vibration element having the above-mentioned structure has the following features. A bandwidth of a frequency allowing for a predetermined level or more of vibratory force to be obtained may be relatively wide, such that stable vibration characteristics may be implemented, and vibrations having high and low frequencies rather than a single frequency within a predetermined frequency range may be variously applied. In addition, since the vibration element allows for rapid operational response characteristics, it may be appropriate for implementing haptic vibrations in mobile devices such as mobile phones, or the like.
Such a piezo-element generally has a rectangular parallelepiped shape in which a length thereof is greater than a width thereof. In this case, since the length of the piezo-element should be relatively long in order to secure sufficient displacement and vibratory force, an overall length of the vibration generating apparatus may be increased and the piezo-element may be vulnerable to impacts occurring when being dropped.
Further, since the overall shape of the vibration generating apparatus is rectangular parallelepiped, the overall volume thereof may be increased, whereby it may be problematic in terms of the miniaturization of components.